The present invention relates to the separation of immiscible liquids. More particularly, the invention relates to removing and recovering liquid hydrocarbons from the surface of natural bodies of water.
As used herein, the terms "petrochemimcal," "oil," and "petrochemical oil" are defined to mean a substance isolated or derived from petroleum or natural gas, and are used interchangeably.
The term "sheen" is defined as an extremely thin film of oil.
The term "baffle" is defined as a plate, wall, screen, or other device to deflect, check, or regulate liquid flow.
The term "compound baffle" is defined as a baffle which defines more than one plane.
The term "solid baffle" is defined as a baffle without an opening therein.
The term "vented baffle" is defined as a baffle which includes at least one opening through which a liquid may flow through the baffle.
As the problem of oil spills has intensified, so too have efforts to provide technology to clean up such spills for the sake of environmental protection, and to recover the oil for the sake of energy and fuel conservation.
Various equipment has been devised for recovering low-density liquids such as oil from surface water. In most cases the recovery of the oil is required due to the adverse consequences of oil in a water supply. Probably the most widely-used apparatus for this purpose is skimming equipment, which separates the oil from the water by allowing the oil to float naturally to the surface of the water. Conventional skimming equipment uses a weir to separate the oil, which includes some water, from the remaining body of water. Permanent skimming equipment is commonly in place, for example, in waste-treatment ponds adjacent industrial and petrochemical facilities, to recover small quantities of oil discharged with water from the facilities before the water is returned to a river or other water supply.
When oil is unexpectedly encountered on the surface of a body of water, or is encountered in unusually high concentrations, it is often preferable to utilize a power-driven hull to assist in hydrocarbon collection. Such hulls have, for example, been provided with endless belts which are lowered into the water to pick up the oil, which is removed from the belt by a squeegee device or other suitable equipment. The oil thus collected is stowed in a compartment in the hull while the cleaned belt is returned to the water. An advantage of this system is that the hull can be easily steered or manipulated to desired locations on a body of water which evidences large oil slicks.
Hulls have also been employed for hydrocarbon-recovery systems utilizing a ring-shaped weir or boom to collect the oil within the perimeter of the boom and adjacent the hull, so that the oil can be retrieved at a location adjacent the hull. The oil and entrained water may be drawn into a holding tank in the hull. The oil may be allowed to rise to the surface of the water in the holding tank, so that the oil and some entrained water can be collected in a separate tank while most of the water originally drawn into the hull is recycled to the pond or body of water.
Another type of skimming device is disclosed by U.S. Pat. No. 4,597,863. This hull-like device does not utilize a floating weir, but uses instead the propeller of an engine to draw the surace oil-water mixture into the hull, where the water is separated by an oil-water separator within the vessel. This system has several significant advantages compared to a system which utilizes an external floating boom, particularly in that the hull may be easily manipulated to a location in the body of water where it is most effective. The system is also designed so that the oil slick on the surface of the water will be drawn to the hull.
Although the hydrocarbon system described by this patent has several important advantages over other prior-art hydrocarbon-recovery techniques, it is relatively complex and expensive. Moreover, the unit is intended to prevent a frontal wake and minimize "pushing" the surface water away from the hull during the skimming operation, and its efficiency is limited by either decreased skimming speed or the creation of a frontal wak leading to decreased oil-recovery performance.
By far the most important weakness in the prior art, however, is failure to provide a skimmer or pickup unit designed to operate independently of separator units by remote control, so that the oil collected by the skimmer unit can be collected and transported in containers to the separator unit or units, but which can optionally be connected to or integral with the separator unit. The skimmer unit should, moreover, be capable of being propelled by a powered vessel, or alternatively of being anchored to receive the oil in place, e.g., by channelling booms.
These problems and their solutions are addressed in the present application, which provides written and graphic disclosures of the present invention.